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: he Chestnut Bark L)i 



isease 



A Grave Danger which Threatens 

Our Forest Trees, with 

Its Remedy 



STATE FORESTER'S OFFICE 
BOSTON. MASS. 

F. W. RANE, STATE FORESTER 




BOSTON 

WRIGHT & POTTER PRINTING CO.. STATE PRINTERS 

18 POST OFFICE SQUARE 

1911 



Approved by 
The State Board of Publication. 









K 



J THE CHESTNUT BARK DISEASE. 



The Disease at^d its Method of Attack. 

The State Forester wishes to call the attention of the citizens 
of the Commonwealth to a serious disease of the common chest- 
nut (Castanea dentata), — a disease which has been working, 
for some time in the States of New York, New Jersey, Con- 
necticut and Pennsylvania, and which has been found to be 
slowly gaining a foothold in Massachusetts. This disease is 
caused by a fungus known botanically as Diaporthe parasitica 
(also as Valsonectria parasitica), and grows in and derives nour- 
ishment from the tissues of the inner bark of the chestnut tree. 
The fungus is conveyed from one place to another by means of 
" spores '' or fruiting bodies, which are analogous to seeds in the 
higher orders of plants. These spores, being small and very light, 
are easily carried long distances by the wind, and when blown 
against a chestnut tree find lodgment in any wounds, of which 
even the healthiest tree often has a great many, that may be in 
the bark. It makes no difference with the disease whether the 
spores find a refuge in the tissues of the thick bark of the trunk 
or the thinner bark of the small twigs, — the fungus develops 
equally well. It is true that in localities where the disease is 
rare the spread is slow, but the fact that it can increase to an 
alarming rate has been proved in our sister States, where it is 
no exaggeration to say that in certain sections the chestnut is 
becoming extinct. 

Growth. 

The spores having gained an entrance, the fungus begins to 
spread by sending out many small fibers, much in the same way 
that a plant sends out roots. These fibers, pushing about and 
through the growing cells of the tree to obtain nourishment, form 
a close network which soon saps the life of the section where 
they are. 



j^ow, the serious part of this process of growth, looked at from 
the tree standpoint, lies in the fact that the fungus shows a 
marked tendency to gTow around the infected branch or stem, 
thus girdling it, and killing all growth above that point. When 
this happens to the trunk of a tree it is easily seen that it becomes 
a serious matter. 

Furthermore, the trunk of a tree may be infected by spores 
coming from diseased parts of its own branches, thus multiplying 
the disease within itself so to speak. 

Appearance of Diseased Parts. 

The following features are characteristic of the external ap- 
pearance of the diseased tree. The outer bark over the diseased 
part is of a slightly reddish tinge, more so than the rest of the 
bark, and as the disease progresses this reddish area becomes cov- 
ered with yellowish, brownish, or orange-colored pustules. Fur- 
ther, in damp weather or damp situations the spores are often 
extruded in the form of greenish-yellow " strings." The bark 
splits open up and down the length of the infected spot and often 
shows a swelled appearance. The cracks are filled with twisted 
and criss-crossed fibers of a slightly yellowish color. Among the 
smaller branches the cracks are of course less visible, but they 
still occur. 

It should be here stated that these same characteristics may 
be the result of the work of other species of fungi than the one 
in question, and therefore, in order to be sure, specimens should 
be sent to a botanist for a microscopic examination. Such iden- 
tification will be gladly made by the Bureau of Plant Industry, 
United States Department of Agriculture, Washington, D. C, 
or by the Massachusetts Agricultural College, Amherst, Mass. 

Time for making Observations. 
The best time for seeing the evidences of the work of this 
fungus is the season now approaching, viz., in the spring, when 
the leaves begin to appear. The reason for this is not that the 
disease does the greatest amount of damage at this time, but be- 
cause trees that have been injured the previous season by having 
much of their live tissue destroyed, instead of putting forth 




Two trees killed by the disease. Note the dilapidated or shreddy appearance of the bark 
and the few persistent dead leaves; also, portion of upper part of left-hand tree, where 
bark is falling off. (All photographs taken at Wilbrahani, Mass., Feb. 23, 1911.) 




Infested trunk, showing how bark splits open. 
(This is a nearer view of section marked " y " 
in photograph to the left.) 



Infested stem. The fungus 
tends to girdle the dis- 
eased portion rather than 
to extend up and down, 
"x" and "y" are dis- 
eased sections. 



healthy new leaves can produce only sickly and stunted foliage^ 
the extent of the blighted area depending on whether the main 
stem or only a branch was attacked. 

Methods of Control. 
It should be understood that there is no known method of cur- 
ing the disease, or of saving woodland once it has become thor- 
oughly infested. The experience of other States has proved 
this. 'Nov is it possible to save single trees, if badly diseased^ 
except at great expense, and even then the chance for failure is 
great, owing to the impossibility of locating all the infected 
spots. 

Vigorous Measures needed in Early Stages. 

To check its spread at the beginning of its entrance into a 
locality is, therefore, the only hope, and this hope is considered 
a strong one by those who have studied the disease most. 

Dr. Haven Metcalf, who is the pathologist in charge of inves- 
tigating this blight for the government Bureau of Plant Indus- 
try, and who has spent a great deal of time in this work, states 
that " in all cases we know of where the disease has been care- 
fully eradicated, in localities where it has just appeared, the 
work has been very successful ; so that we feel warranted in 
advising a very considerable outlay of energy to eradicate the 
disease at the outset." 

Methods of Eradicating. 
Inspection of Nursery Stock. 
There are several ways of going about the eradication of the 
blight. All chestnut nursery stock should be carefully inspected 
for signs of the disease, as such stock has heretofore apparently 
been one of the chief agencies of spreading the fungus. This 
precaution should be taken by nurserymen and purchasers alike. 

Prompt Destruction of Diseased Trees, 
A careful inspection of trees for evidences of the disease 
should be made by all owners of chestnut woodland during the 
months of May and June, and any tree found infected should at 



once be cut down, the wood put into marketable form, and all 
brush, and if possible all patches of diseased bark, burned at the 
first opportunity. If this is not done, the down tree merely 
becomes a center of infection for the rest of the woods, as it is 
known that the fungus may live on dead bark for at least six 
months after cutting. 

In answer to the question as to whether sprouts from the 
stumps of infected trees that have been cut will also themselves 
be infected, it should be said that for the first year at least they 
will not be, but after that they should be carefully examined for 
signs of the disease. 

Treatment Other than Cutting. 
Spraying. 

Experiments have shown it to be a matter of doubt as to 
whether the spraying of infected trees is of any avail against 
this fungus. It is possible, however, that in the case of valuable 
shade trees very frequent sprayings might have a tendency 
toward preventing infection. 

Broken limbs, woimds, cracks and crotches of branches are 
fruitful sources of attack, and the fungus should be looked for at 
these points. 

Local Cutting of Infected Spots. 

The other method of individual treatment that has proved suc- 
cessful, though only in the case of valuable trees, where the ex- 
pense was warranted, is the one of cutting and removing all 
patches of diseased bark and carefully protecting the exposed 
surface with a coat of tar or paint. This treatment must be 
thorough, and even then it will do no good if the disease has 
progressed too far. Infected branches should be removed alto- 
gether, at a good distance below the point of infection, and any 
bark cutting should be done at least an inch beyond and outside 
of the discolored area, which shows the location of the fungus. 

A tree that has been already girdled should be cut down at 
once, and trees under treatment should be inspected frequently, 
say about June 1, July 15 and September 1, or oftener in wet 
weather. 



Co-operation Necessary. 
It is believed that by carefully following the foregoing instruc- 
tions the disease can be kept under control in Massachusetts, 
with the constant hope that some natural enemy will appear to 
assist in the work. No controlling enemy, however, is known at 
present. All persons are therefore urged to do their utmost, 
either by reporting cases to this office or by actively using some 
of the above measures of control, to aid in checking this enemy 
of one of our best timber trees. 

Bibliography. 
Eeference is made to the publications of the United States 
Department of Agriculture on this subject, especially Bulletin 
141, Part v., of the Bureau of Plant Industry, from which 
several extracts, including quoted passages in this pamphlet, have 
been taken (those who are interested are advised to obtain a copy 
of this bulletin) ; also to a report of the Main Line Citizens' 
Association of Haverford, Pa. 

CONCLUSIOI!^. 

Lest the serious results of this disease be underestimated, the 
following instances of its work in other localities are cited : — 

" A survey of the Forest Park, Brooklyn, showed ' that 16,695 chest- 
nut trees were killed in the 350 acres of woodland in this park alone. 
Of this number, about 9,000 were between 8 and 12 inches in diameter, 
and the remaining 7,000 or more were of larger size.' " 

" In a recent publication Dr. W. A. Murrill estimates the financial 
loss from this disease ' in and about New York City ' at ' between five 
and ten million dollars.' " 

With this loss in a city it can readily be seen what an enor- 
mous loss would occur should the disease become prevalent in the 
woodlands. 

It becomes a question, therefore, as to which is the better 
economy, — to do nothing, and lose our chestnut trees, or to do 
our utmost at this early stage, with a fair chance of saving them. 



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